It's already there.
840
840
27844 rounds to30 000 to the nearest ten thousand28 000 to the nearest thousand27 800 to the nearest hundred27 840 to the nearest ten
840
840
840
840
840
840
It is already rounded to the nearest ten as 840
850
840
15 840 rounds to:0 to the nearest hundred thousand20 000 to the nearest ten thousand16 000 to the nearest thousand15 800 to the nearest hundred15 840 to the nearest ten and whole number/unit
840
145
To the nearest ten, 840. To the nearest hundred, 800. To the nearest thousand, 1000.
It is: 850